The present invention relates to a printed circuit board processing machine and more particularly to a printed circuit board processing machine suitable for independently controlling a plurality of spindles to reduce the machining time of printed circuit boards to improve machining efficiency.
In drilling of printed circuit boards, reduction of drilling time has almost reached its limits. Therefore, in order to further reduce machining time and improve machining efficiency, it is necessary to reduce traveling time of the spindle that travels among machining positions.
Therefore, a printed circuit board processing machine in which a plurality of machining zones are set along a spindle travel direction (Y direction) on a single printed circuit board and spindles respectively corresponding to the machining zones are arranged for independently movement to shorten traveling distances of the spindles are shorten of the spindles, thereby improving machining efficiency is proposed in, for example, JP-A-64-58405. This printed circuit board processing machine has a structure shown in FIG. 7.
Reference numeral 1 denotes a bed. A table 2 is moveably supported by guide means 3 fixed to the bed 1 so that it can travel in a direction of arrow X, and is driven by a feed screw mechanism including a feed screw 4. Drill supply devices 5R, 5L are fixed to the table 2 with a predetermined interval.
A cross rail 6 is fixed to the bed 1 so as to straddle the table 2. Sliders 7R, 7L are supported for movement in an arrow Y by guide means 8 fixed to the cross rail 6, and are independently driven by respective feed screw mechanisms including respective feed screws 9R, 9L and motors 10R, 10L.
Saddles 11R, 11L are supported for movement in an arrow Z by respective guide means 12 fixed to sliders 7R, 7L, and are driven by respective feed screw mechanisms each of including a feed screw 13 and a motor 14.
Spindle units 15R, 15L, each of which comprises a spindle provided with a chuck for detachably supporting a drill as well as a motor for rotationally driving the spindle, are respectively supported by saddles 11R, 11L. A printed circuit board 16 is placed on the table 2 and is machined.
With this structure, the machining zone of the printed circuit board 16 is divided into a left zone and a right zone at a substantial center thereof. The spindle unit 15R processes the right machining zone and the spindle unit 15L processes the left machining zone. Thus, it is possible shorten the travel distance of each spindle unit 15R, 15L necessary for machining the printed circuit board 16 by half of the structure in which the entire machining zone is processed by a single spindle unit. Also, since it is possible to independently locate the spindle units 15R, 15L for machining, machining efficiency can be improved.
However, since this machine drives multiple sliders independently, the feed screw mechanisms for driving the sliders in the Y direction must be provided as many as the number of sliders. Consequently, it becomes difficult to secure space for feed screw mechanisms on the cross rail if the number of sliders is three or more. It is also difficult to keep the precision of three or more feed screw mechanisms uniform.
In the light of the circumstances described above, an object of the present invention is to provide a printed circuit board processing machine capable of using three or more spindle units independently driven in the Y direction and further improving machining efficiency.
A printed circuit board processing machine according to the present invention comprises a table that can travel in a X-direction carrying a printed circuit board thereon; a cross rail arranged so as to straddle the table; a plurality of sliders supported for independently movement in a Y-direction by the cross rail; a plurality of spindles supported for movement in a Z-direction by the sliders; a magnetic rail of a linear-motor fixed to the cross rail; and a plurality of coils of the linear-motor fixed to the sliders so as to oppose the magnetic rail.
The printed circuit board processing machine further comprises a linear encoder fixed to the cross rail; a plurality of linear encoder heads fixed to the sliders so as to correspond to the linear encoder; a plurality of first dogs for returning to home positions, fixed to the cross rail so as to correspond to the sliders; a plurality of first sensors fixed to the sliders so as to correspond to the first dogs; a plurality of second dogs for interference prevention, fixed to one of adjacent sliders; and a plurality of second sensors fixed to the other of the adjacent sliders so as to correspond to the second dogs.